This invention relates to solid-state lasers and more particularly to a solid-state laser operative in the mid-infrared spectrum.
Heretofore, gas lasers have been made which are capable of operation in the infrared region of the spectrum and solid-state lasers have been made that operate below the mid-infrared region. The standard approach for exciting solid-state lasers is to use broadband incoherent sources to pump the energy levels in rare earth, transition metal or actinide activator ions. It has been determined that for wavelength transitions greater than 3 .mu.m, the decay is predominantly non-radiative. It has been concluded by others in the laser field that laser emission by solid-state lasers beyond 3.3 .mu.m is unlikely since fluorescence at these long wavelengths is overwhelmed by non-radiative relaxation due to multiphonon emission. Prior art relating such a teaching is found in an articler, "Laser Emission at 3 .mu.m from Dy.sup.3+ in BaY.sub.2 F.sub.8 ", by L. F. Johnson and H. J. Guggenheim, Applied Phys. Lett., Vol. 23, #2, pp 96-98, 15 July 1973. The prior art herein relates to Dy.sup.+3 emission enhanced by Er.sup.+3, Yb.sup.+3, Tm.sup.+3, or Ho.sup.+3. A comparison of radiative and non-radiative relaxation rates for rare-earth ions in BaY.sub.2 F.sub.8 indicates that an extension of laser emission to 4 .mu.m is unlikely.